How RequestNavigate works called from external thread

I implemented the prism navigation and the RequestNavigate works well whenever it is called from a button event or something like this. Now I want to implement a demo mode where every view is called from an thread without a user action. But this does'nt
work. The RequestNavigate was never called. Got anyone a solution?

Since navigation is intended to update the UI, the RequestNavigate
method should be called from the UI thread. In order to achieve that, you could use a
Dispatcher to call that method from the UI thread, or extend the RegionNavigationService
(which can be found in the Regions folder of the
Prism.Silverlight project of the Prism Library) to internally use a Dispatcher to execute the navigation in the UI thread.